1. Scientific Measurement
Chapter 3

2. Importance of measurement: WHY BOTHER???
We deal with small numbers!!! Track, horse races, etc.
Qualitative vs. quantitative measurements
Qualitative = descriptions, non-numerical
Quantitative = measurements, numerical and units
Scientific notation EX: X 103 or 6.59 X 10-3
Number greater than or equal to one, less than 10
Exponent positive or negative
Rules
multiplication/division – deal with the coefficients 1st, then add/subtract exponents.
addition/subtraction – make the exponents the same first (violate rule for n between 1 – 10), then just worry about coeffients

3. Uncertainty in measurements
Accuracy – how close a measurement is to “correct”
Precision – how close measurements are to each other
Accepted value (theoretical or book value) – “correct” value
Experimental value – actual value obtained
Error = experimental value – accepted value; will be positive or negative depending on relationship to accepted value
Percent error = | error___|____ X 100%
accepted value

4. Significant figures – all measured values PLUS an estimated number
Every nonzero digit is significant: 117
Zeroes between nonzeroes are significant: 907
Leftmost zeroes in decimals are placeholders, not significant: (you can get rid of them in sci notation)
Rightmost zeroes in decimals are not placeholders, significant: (you can’t get rid of them in sci notation)
Rightmost zeroes of understood decimals are placeholders, not significant: 907,000
Infinite significant digits
counted objects: 23 students
defined quantities: 60 seconds in 1 minute

5. Rounding – using significant figures in calculations
look at each number, find out the least # of significant digits; round to that # and add zeroes.
If # is less than 5, drop it; greater, round up; if = 5, look to even/odd rule – even leave it, odd round it
Addition/subtraction
answer rounded to least number of decimal places
Multiplication/division
answer rounded to least number of significant digits

6. SI system Length = meter Volume = m3 (or L = dm3) Mass = kilogram
Density = g/cm3
Temperature = Kelvin
Time = second
Pressure = pascal (or atmospheres, mm mercury)
Energy = joule (or calories)
Amount of substance = mole
Luminosity = candela
Electric current = ampere

7. Prefixes mega (M) = 106 kilo (k) = 103 Hecto (h) = 102 Deka (D) = 101
deci (d) = 10-1
centi (c) = 10-2
milli (m) = 10-3
micro (u) = 10-6
nano (n) = 10-9
pico (p) = 10-12

8. As the saying goes… Kanga r o o s Hopping Down t h e Mountain drinking
chocolate
mi l k

9. Convert: 15 grams to kilograms .37 milligrams to Hectograms
7.43 centigrams to Dekagrams
8.4 micrograms to kilograms

10. Conversions 1 L = 1000 mL = 1 dm3 1 cm3 = 1 mL
weight – force of gravity on an object
mass – amount of matter in an object

11. Definitions density = mass/volume
specific gravity = density of substance/density of water (which is 1 g/cm3)
used as a comparison to water, determines integrity of substance
car battery
blood disease detection
transmission fluid
temperature
Kelvin scale based on absolute zero K = 0C + 273
Celsius scale based on freezing water 0C = K – 273

12. Review for Test Terms – matching with definition
Converting decimal to sci. notation
Significant figures – rounding, etc
Metric conversions
Density formula – finding mass, volume
Temperature conversion – C0 to K, K to C0